VATIS UPDATE Article

High-protein nutrition bars and other shelf-stable, intermediate moisture foods often harden to unpalatable levels during storage; however, a new study conducted by researchers at Iowa State University (ISU), the United States, suggests adding ground extruded milk protein concentrates (MPC) with 80 percent protein can enhance the texture and other sensory attributes of high-protein nutrition bars. For the study, MPC80 was extruded at two different conditions and model high-protein nutrition bars were prepared.

A trained sensory panel and instrumental techniques were used to measure high-protein nutrition bars firmness, crumbliness, fracturability, hardness, cohesiveness and other attributes to characterize texture change during storage. The researchers found extrusion modification, storage temperature and storage time significantly affected the instrumental and sensory panel measured texture attributes. The high-protein nutrition bars became firmer and less cohesive during storage.

When evaluated at the same storage conditions, the texture attributes of the high-protein nutrition bars formulated with the different extrudates did not differ significantly from each other; however, textural differences were noted most of the time between the control and the high-protein nutrition bars formulated with extruded MPC80. An adapted high-protein nutrition bars crumbliness measurement technique produced results that were correlated with sensory panel measured crumbliness (r = 0.85) and cohesiveness (r = -0.84).